1988 wheel horse 520 hc power lose

zlock24 · Oct 10, 2011

My 1988 wheel horse 520 hc with a 60" mmm has at least 1200 hours on it (not 100% sure) recently it has lost power, it stalls out going up hills (hst transmission) an it burns oil kinda of bad ( have to add a quart of oil about every 10 hours) is there anything I can do to help this 20 horse onan, or is this air cooled engine at the end of it's life?

Tollster · Jan 8, 2012

zlock24 said:
My 1988 wheel horse 520 hc with a 60" mmm has at least 1200 hours on it (not 100% sure) recently it has lost power, it stalls out going up hills (hst transmission) an it burns oil kinda of bad ( have to add a quart of oil about every 10 hours) is there anything I can do to help this 20 horse onan, or is this air cooled engine at the end of it's life?

I would try to rebuild it, new rings, valves ect. Depending on how good a shape its in, it would still be much cheaper than a new one, and in the long run, its twice the tractor compared to anything you can touch for under 4k today I would imagine. One look at the rear axle will tell you that.
I think norther hydraulic may even be able to set you up with a new onan if you wanted to go that route. I never did it, but imagine you could pull it off. They are worth fixing, keeping the deck working seems to be the toughest part.

546cowboy · Jan 21, 2012

If you aren't an experienced mechanic don't even try to rebuild it. You can only get Onan parts from one place and that is owned by Cummins.

Rods are $80+ ea., piston with rings is around $120 ea., a gasket set is I believe $132. Now that's just the basic stuff and then you will have machine shop work on top of the parts. As you can see before you know what happened you'll have close to $1000 in it.

You could buy a rebuilt one for about $1100 or watch Ebay and Craigslist for one or swap a Honda in it for about $1800.

I do have three 520H's so I know what I'm talking about. There is nothing like them though short of a diesel. Once you've had a good one nothing else compares.